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Chapter 3

Psychology 2042A/B Chapter Notes - Chapter 3: Fetal Alcohol Spectrum Disorder, Somatic Nervous System, Peripheral Nervous System

10 pages112 viewsFall 2011

Department
Psychology
Course Code
Psychology 2042A/B
Professor
Richard Brown
Chapter
3

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Psych 2042A
Chapter 3: Biological and Environmental Context of Psychopathology
Brain and Nervous System
Brain Development: Biology and Experience
much of early growth is biological, but the influence of experience increases over
time
the brain contains millions of supporting cells, the glial cells, and neurons that are
specialized to transmit impulses within the nervous system to and from other body
parts (as if sending messages throughout the body)
different brain areas develop in spurts more rapidly than others
interaction of the nervous system has been shown to depend on the interaction of
biological programming and experience
early shaping of the brain relies in part on the mechanism of pruning - the
elimination of unneeded cells and connections
Structure
the brain and the spinal cord form the central nervous system
anything outside the central nervous system is called the peripheral nervous
system - composed of nerves outside the central nervous system
peripheral nervous system is composed of autonomic and somatic system
autonomic nervous system is concerned with involuntary regulation (i.e.
arousal and emotion)
somatic nervous system involves sensory organs and sensing voluntary
movement
the entire nervous system works with the endocrine system - a collection of
glands intricately involved in bodily functions through the release of hormones.
the brain: has 3 parts that are interconnected and work together - the hindbrain,
midbrain and forebrain
hindbrain: pons, medulla, and cerebellum
midbrain: contains the fibers that connect the hindbrain and upper brain regions
forebrain: consist of the two cerebral hemispheres connected by the corpus
callosum
below the cerebral hemispheres are the subcortical structures: thalamus and
hypothalamus
thalamus: processing and relaying information between the cerebral
hemispheres
hypothalamus: regulates basic urges such as hunger, thirst, and sexual activity
Neurotransmission
all cells have 3 parts: body, dendrite, and axon
communication between the neurons (cells) occurs within a gap called the
synapse
dendrites of a neuron receive chemical messages from other neurons that
result in an electrical impulse being send down the axon
when the electrical impulse reaches down the axon, it releases chemicals
called neurotransmitters (i.e. GABA, serotonin, epinephrine, glutamate)
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Nervous System and Risk for Disordered Functioning
nervous system is an important factor for determining psychological functioning and
behaviour
dysfunction or harm can also be attributed to events that occur during pregnancy
(prenatal), at the time of birth (perinatal), or during later development (postnatal)
Prenatal Influences
poor maternal diet and health can put the developing child at risk
exposure to prenatal stress can also the fetal biological system (makes them
susceptible to later psychological problems)
a variety of agents (harmful substances) can enter the motherʼs bloodstream -
these are called teratogens (i.e. alcohol, drugs, rubella, syphilis, and gonorrhea)
i.e. a result of alcohol abuse during pregnancy is fetal alcohol syndrome
(FAS)
have facial abnormalities (flat upper lip, narrow eye openings)
impaired motor skills and unusual gait (manner of walking)
heart, kidneys, eyes, ears, and other organs are affected
learning disabilities, cognitive impairments in memory, comprehension, etc
hyperactivity, impulsivity, oppositional behaviour, conduct disorders
** as little as one drink a day can alter oneʼs infant detrimentally - no safe
level of maternal consumption
teratogens are associated with malformation, functional and behavioural
impairment, low birthweight, and fetal death.
amount of exposure, timing of exposure, and the length of exposure to teratogens
makes a difference in the outcome
in general, when structures and systems in the body are rapidly developing, they
are at higher risk for being adversely affected by a teratogen
it is difficult to conduct research with teratogens because it is simply unethical to
conduct a controlled study of exposing pregnant women to teratogens
teratogens tend to cluster (i.e. prenatal use of illicit substances is often associated
with alcohol and cigarette use)
Perinatal and Postnatal Influences
excessive medication given to the mother, unusual delivery, and anoxia (lack of
oxygen) can result in neurological problems with the baby
prematurity, low birth-weight, and low birth-weight relative to length of gestation
can also affect the baby
in the US, 12% of infants are born prematurely (less than 37 weeks into gestation)
and 7.5% are born with low birthweight
some postnatal factors include: malnutrition, accident, illness, or poisoning
i.e. lead poisoning - affects attention and cognitive development
whenever brain damage occurs in youth, major concern is the degree to which the
resulting problems can be remediated - plasticity - the brainʼs ability to recover is
controversial
some say that young immature nervous system is very skilled in transferring
functions to undamaged brain areas
on the other hand, some say that damage to the immature brain may set up a
cascade of interferences with future brain development
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Genetic Context
genetic material is in the form of chromosomes, containing DNA - functional
segments of genes
chromosomes may exchange genes (replication, transcription) and can change genes
(mutation)
the study of genetic influences on individual differences in behaviour is known as
behaviour genetics
genes act indirectly and in complex ways to guide the biochemistry of cells
genetic code - refers to the order in which the four nucleotides appear on the DNA
the genes that carry the code are very critical to development as it goes through
replication, transcription, and translation
only some of the coding genes are expressed (either turned on or off)
but there are also noncoding genes that are involved
genotype - genetic endowment ; phenotype - the observable characteristics of a
person
Single-Gene Inheritance
Gregor Mendel hypothesized that each parent carriers two hereditary factors (two
genes/alleles), but passes only one to the offspring
from a parent: one gene is dominant (the trait is displayed), and one gene is
recessive (displays itself only when transmitted by both parents)
Huntingtonʼs disease - transmitted dominantly
Tay-Sachs disease - transmitted recessively
one way to establish single-gene inheritance on a specific disorder is to identify a
person with the disorder (the index case or the proband) - and determine whether
a known pattern of single-gene inheritance runs in the family
Multiple-Gene Inheritance: Quantitative Methods
multiple genes are more often implicated in complex human characteristics (i.e.
intelligence and psychological disorders)
multiple genes can be referred to as quantitative trait loci (QTLs) - these have
small influences but can combine to create a large effect
sometimes, one gene is insufficient to carry out the disorder in the person
this is less predictable than single-gene inheritance
quantitative genetics assesses heritability - the degree to which genetic influence
accounts for variance in behaviour
results suggest that with a few exception, heritability for psychological disorders
is usually less than 50% - meaning that psychological disorders can most be
attributed by environmental influences
Shared environmental influences: influences that affect family members
developing in similar ways
Nonshared environmental influences: influences that are different for
children growing up in the same family - siblings result differently
Searching for Genes: Molecular Methods
Linkage Analysis: is to reveal the location of a defective gene, determines
whether a specific disorder appears among family members in the same pattern as
a genetic marker
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